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Hi Russ
I'm eagerly awaiting Legato, but....
It's not easy to adjust the regulators I'm using to +\- 12V to suite Legato. Possible, but involved, and certainly not suited to an easy comparison of Legato and IVY II.
Would Legato tolerate a 15V supply, and would there be any downside?
Thanks
Paul
I'm impressed that you've tried to develop an op amp-free BAL to SE converter for Legato. Any progress? The op amp bothers me. Having heard IVY III I'd have to confess that this is irrational, but I just can't help it
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Quote:I'm impressed that you've tried to develop an op amp-free BAL to SE converter for Legato. Any progress? This is essentially what the Ventus does, though it has a big diamond buffer at the output.
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It is possible to make it suitable for 15V. You would want to increase the size of some of the resistors. Noise might suffer a little and heat at the transistors will be a bit more, but likely still acceptable. AS Brian said, you could definitely use Ventus after the balanced outputs of the Legato. Edited by user Wednesday, May 26, 2010 5:12:21 AM(UTC)
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Rank: Advanced Member
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Hi Brian
I'll check out Ventus, thanks
Hi Russ
Any guidance on this would be gratefully received. I'm sure there are others who would appreciate the option of 15V operation, at least initally, to facilitate comparison with IVY III
Thanks
Paul
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For Placid, it's just a matter of turning a screw :)
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Hi Brian
I know, don't rub it in! :-)
There're higher powered versions of the regs I'm using, which are similarly easy to adjust. But I went for a lower powered three legged drop in version, which would need resistors changing, and also a reduction in input voltage to avoid dissipation issues. All trivial- just involved
Paul
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Hi
How much current does Legato need?
Thanks
Paul
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A lot :)
Close to 300ma per rail at 15V rails. A bit less at 12V rails.
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300ma per channel or for stereo?
The legato sounds exciting Russ. Any idea when you will "introducing" or releasing more information (eg schematic, part list, layout)?
Hoping that the kits will be available soon...
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Legato is a balanced and SE stereo board. 300ma per rail is for the whole shebang. This may change slightly, but not much. I have been busy the last few weeks tuning the design. I just ordered PCBs so. We should be selling them in the next few weeks. I have gone through a few prototypes trying to get it to my liking. :) I want it to be both easy to build and sound incredible. I can't wait till you guys can hear what I am hearing. It is pretty awesome. Edited by user Tuesday, June 15, 2010 8:36:22 PM(UTC)
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Hi Russ
Now even more eagerly anticipated!
300mA in total. Can the L, R and Bal SE stage supplies be separate- i.e. three supplies in total? Then the max current required per supply would be ~135mA?
You mention a +/-15V supply. So you've factored this in as an option? Does it sound any different to 12V?
"Pretty awesome". Now better than IVY III, or still just a different excellence? :-)
Thanks
Paul
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"Better" well, maybe. That's really subjective.
I really love it, but I can't say I like one better than the other.
The power scheme is identical to IVY-III. You can split all three and even completely omit the BAL/SE stage if you like.
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Hi Russ
Do you hear any differences between 15V and 12V operation? Assuming I've understood you correctly, and you have implemented a 15V version?
Thanks
Paul
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There is no real audible difference that I have been able to discern yet. It goes from about -116db THD at 15V to -113db at 12V. :)
The Board runs a bit hotter at 15V, but both voltages are perfectly safe.
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Russ,
I was curious which stage is drawing that much current. Is it the optional buffer? 15v+15v @ 300ma = 9 Watts and I dont remember seeing any heatsinks in your pics.
You also mentioned that the legato input impedance is less than 1 ohm. Do you know what the impedance is for the IVY III?
Any chance of seeing a schematic? :)
BTW my buffalo II was just delivered by the postman an hour ago. I am one happy man!
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The heat dissipated by quite a few components. :)
Most of the load is the I/V stage. If you omit the buffer it is less by about 1/3.
Nothing is is thermally stressed. Most of the load is taken by 12 1W resistors. The most any single component dissipates is about 600mw. And that is a resistor.
I will post the schematic at some point. But not yet.
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Hi Russ
Now Legato is finalised, what are it's exact current requirements, at +/-15V and +/-12V? Total, perrail, and split down to each channel and the Bal to SE stage?
Thanks
Paul
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I have not tried it with stock parts yet. Brian is still ordering those. So anything I measure right now will be a bit off. :)
Brian will build one of each configuration up (with and without buffer) and then we can measure the current at 15 and 12V.
Cheers!
Russ
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I have not tried it with stock parts yet. Brian is still ordering those. So anything I measure right now will be a bit off. :)
Brian will build one of each configuration up (with and without buffer) and then we can measure the current at 15 and 12V.
Cheers!
Russ
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I am building my Legato and thinking that I would like to use the Ventus for balanced to single ended conversion. Would I be better off installing the output buffer on the Legato to drive the stock Ventus, or increasing the input impedance of the Ventus to 4.7K by repurposing R9-R16 from the balse that came with the Legato? Would I need to change anything on the Ventus other than replacing R2-R5 and changing CC2 and CC3 to about 10 pf?
Lastly I am building this as a dual mono and want single ended output as well as balanced so I imagine a third stock Ventus could be fed from an additional 21 ohm split off of the outputs of the first two. Do you see any problems with this idea? Looks like I will need six Ventus boards. Any idea when they may be available?
Thanks again for such a great sounding project.
Stephen
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